Voltage Range K Factor understanding
Voltage Range K Factor understanding
(OP)
Hello all. I am trying to gain a better grasp of K-factor as associated with breakers and MCCs. It was mentioned to me by an associate that he had 15kV equipment being operated at 6.9kV so the K-factor would affect the short-circuit current available. This is a new subject to me so I am hoping someone can help with links to good sources or advice. Thanks.






RE: Voltage Range K Factor understanding
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Voltage Range K Factor understanding
RE: Voltage Range K Factor understanding
New ANSI standards no longer use the K-factor, but it would still apply to any breakers tested and rated by that method.
As mentioned, this is unrelated to Transformer K-rating.
RE: Voltage Range K Factor understanding
Thanks! I think I understand it now with your and davidbeach's feedback.
RE: Voltage Range K Factor understanding
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Voltage Range K Factor understanding
Although you've said it (k-factor) is not included in the new ANSI-standards, does some American switchgear manufacturers still use it?
Never heard of it (in the breaker-world) before.
Thanks
Regards
Ralph
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RE: Voltage Range K Factor understanding
K factor was for air and oil based circuit breakers with interrupting ratings given in short circuit MVA. As the operating voltage decreased, the short circuit current capability increased up to some maximum value given by the K factor. The interrupting MVA was constant down to some minimum voltage so the current value could be increased.
Oil and Air Blast circuit breakers could dissipate a given amount of arc energy. The interrupting current levels were not the limiting factor. The arc energy was the limit.
SF6 and vacuum interrupters use a different arc interruption phenomenon. They are limited by the current and not the arc energy. Their interrupting rating does not increase as the application voltage level drops. K=1.0
See Powell Electric’s website for a good white paper on this.
http://www
RE: Voltage Range K Factor understanding
Thanks again for the discussion. GE still mentions K-factor in there literature.
http://
Glad I wasnt the only 'new guy' who had never heard of this. Thank you again.